MEMS auto focus miniature camera module with fixed and movable lens groups

ABSTRACT

A MEMS auto focus miniature camera module includes an image sensor and an optical train including at least one movable lens and one or more fixed lenses or fixed lens groups on either side of the movable lens. The movable lens provides an auto focus feature of the camera module. A MEMS actuator translates the movable lens through an auto focus range to adjust focus.

PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 USC § 119 toU.S. provisional patent application No. 61/643,331, filed May 6, 2012;which is incorporated by reference; and this application is acontinuation-in-part (CIP) of U.S. patent application Ser. No.13/792,132, filed Mar. 10, 2013, which claims priority under 35 USC §119 to U.S. provisional patent application No. 61/609,293, filed Mar.10, 2012; which is incorporated by reference; and

This application is related to a series of applications filed on Mar.10, 2013, including Atty. Docket IO2-0382-US-03, application Ser. No.13/792,132, entitled, MINIATURE CAMERA MODULE WITH MEMS-ACTUATEDAUTOFOCUS; Atty. Docket IO2-0382-US-04, application Ser. No. 13/792,137,entitled, MINIATURE MEMS AUTOFOCUS ZOOM CAMERA MODULE; Atty. DocketIO2-0382-US-05, application Ser. No. 13/792,139, entitled, CAMERA MODULEWITH MEMS AUTOFOCUS AND ZOOM; Atty. Docket IO2-0382-US-06, applicationSer. No. 13/792,140, entitled, MEMS AUTOFOCUS CAMERA MODULE WITHALIGNMENT REGISTRATION; Atty. Docket IO2-0382-US-07, application Ser.No. 13/792,145, entitled, CAMERA MODULE WITH PROCESSOR-BASEDMEMS-ACTUATED AUTOFOCUS; Atty. Docket IO2-0382-US-08, application Ser.No. 13/792,147, entitled, MEMS AUTOFOCUS CAMERA MODULE WITH MULTIPLELENS GROUPS; Atty. Docket IO2-0382-US-09, application Ser. No.13/792,148, entitled, MEMS AUTOFOCUS CAMERA MODULE WITH FIXED ANDMOVABLE LENS GROUPS; Atty. Docket IO02-0382-WO-01, application Ser. No.______, entitled, MINIATURE CAMERA MODULE WITH MEMS-ACTUATED AUTOFOCUS;and

This application is related to a series of applications filed on May 6,2013, including Atty. Docket IO2-0382-US-10, entitled, “MEMS AUTO FOCUSMINIATURE CAMERA MODULE WITH FIXED AND MOVABLE LENS GROUPS”; Atty.Docket 102-0382-US-11, entitled, “MEMS AUTO FOCUS MINIATURE CAMERAMODULE WITH ABUTTING REGISTRATION”; Atty. Docket IO2-0382-US-12,entitled, “MEMS AUTO FOCUS MINIATURE CAMERA MODULE WITH PASSIVEALIGNMENT”; Atty. Docket 102-0382-US-13, entitled, “MEMS AUTO FOCUSMINIATURE CAMERA MODULE WITH MULTIPLE REGISTERED LENS GROUPS”; Atty.Docket IO2-0382-WO-02, entitled, “MEMS AUTO FOCUS MINIATURE CAMERAMODULE WITH FIXED AND MOVABLE LENS GROUPS”; each of which areincorporated by reference.

BACKGROUND

A camera is a device for capturing images. A traditional camera usesfilm and photographic paper as the capture medium. More recently, theelectronic camera has been invented that permits the capture of imagesin electronic form, principally as files that can be read, processed anddisplayed by other electronic devices.

An electronic camera comprises two principal components. These are anoptical train and an image sensor. The optical train typically containsa plethora of optical active elements including, but not limited tobaffles, lenses, apertures, stops, mirrors and the alike. The functionof the optical train is to capture light from the scene of interest andfocus it on to the image sensor with high fidelity. That is, without toomuch distortion, aberration, blurring, ghosting or any of themultiplicity of optical artefacts that are known and which serve todegrade the fidelity of the captured image. The image sensor is anelectro-optic component, commonly made of silicon. The operation of suchcomponents typically involves dividing the focused image into a largenumber of microscopic portions and recording the colour and illuminationintensity of each. The image sensor then processes this information tooutput a representation of the image in an electronic form. Often theseforms are defined by Standards, such as JPEG, permitting them to bereadily processed and displayed by other electronic devices.

Electronic cameras come in essentially two flavours. These are fixedoptic and variable optic. In a fixed optic camera all the elements ofthe optical train are fixed in functionality and location in the cameraat the time of manufacture. This means the performance of the opticaltrain and hence the camera is invariant. Because the primary function ofany camera is to capture focused images, cameras of this type are oftenreferred to as ‘fixed focus’. Typically the focus of a fixed focuscamera is set at about 1.2 m from the camera. This means that allobjects in the range from 60 cm to many tens of metres away haveacceptable fidelity in the captured image. In a variable optic camera,one or more elements of the optical train may be designed to permitvariation in function, functionality or location. For example anaperture placed at the front of an optical train has a major influenceon the quantity of light that reaches the image sensor and hence thebrightness or darkness of the resulting image. By suitable adjustment ofthe aperture, one camera can produce images of good fidelity inconditions where the scene is brightly lit, for example in brightsunshine, and where it may be dimly lit, for example in moonlight.

Another example of a variable optic camera is one wherein the positionof the entire optical train can be moved along the optical axis of thecamera. This alters the focus of the camera permitting objects that arealmost any distance from the camera to be captured with high fidelity.If the camera operator selects the focus distance by manual adjustmentof the position of the optical train the camera is said to be ‘manualfocus’. Where an electronic system is used to measure the distance fromthe camera of the objects in the scene and is used in conjunction withan actuator to move the optical train, the camera is said to be ‘autofocus’.

It has been found possible to combine many functions in a variable opticcamera. Thus, for example, it is possible to purchase a camera that hassimultaneous autofocus and zoom capability. However combination offunctions like this inevitability results in an optical train ofconsiderable complexity and consequentially size, weight, cost and poorreliability. Consequently improvements in autofocus zoom cameras aredesirable and particularly for miniature cameras that are incorporatedin portable electronics products such as mobile phones.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a MEMS auto focus miniaturecamera module in accordance with certain embodiments;

FIG. 2 schematically illustrates an optical train of a MEMS auto focusminiature camera module in accordance with certain embodiments;

FIG. 3 schematically illustrates a cross sectional view through a MEMSauto focus miniature camera in accordance with certain embodiments,where the optical train has been fabricated as a pre-aligned unitarycomponent in accordance with certain embodiments;

FIG. 4 schematically illustrates a cross-sectional view through theoptical train of a MEM auto focus miniature camera module in accordancewith certain embodiments, particularly illustrating one or more lensesthat are passively aligned and one or more lenses that are activelyaligned;

FIG. 5 and FIG. 6 show examples of possible sequences of steps tofabricate an optical train of a MEMS auto focus miniature camera modulein accordance with certain embodiments.

DETAILED DESCRIPTIONS OF THE EMBODIMENTS

An auto focus camera module and/or auto focus zoom camera module isprovided that includes a camera module housing and an image sensor andoptical train within the housing. The optical train includes multiplelenses configured to provide auto focus and zoom for the camera module,including a first fixed lens group, a second fixed lens group and amovable lens that is disposed between the first and second fixed lensgroups. The movable lens is coupled to an actuator to move the movablelens relative to the image sensor and the first and second fixed lensgroups in an auto focus zoom operation of the camera module. The firstand/or second fixed lens groups may include one or two or more fixedlenses. In one embodiment, both fixed lens groups include a pair offixed lenses.

An auto focus and/or auto focus zoom camera enabled embedded device isalso provided. An embedded device housing contains a processor, a cameramodule and processor readable code for programming the processor toperform an auto focus operation. The camera module includes an imagesensor and an optical train that at least includes a first fixed lensgroup nearest the image sensor and a second fixed lens group, and atleast one movable lens disposed between the first and second fixed lensgroups. The at least one movable lens is coupled to a MEMS actuator tomove the movable lens relative to the image sensor and the first andsecond fixed lens groups in an auto focus operation of the cameramodule.

Another auto focus and/or auto focus zoom camera module is provided thatincludes a camera module housing and an image sensor and optical trainwithin the housing. The optical train includes a first fixed lens group,a second fixed lens group, and at least one movable lens disposedbetween the first and second fixed lens groups. The at least one movablelens is coupled to an actuator, e.g., a MEMS actuator, to move themovable lens relative to the first and second fixed lens groups. Theimage sensor is aligned with the optical train. A processor-readablememory includes code for programming a processor to perform an autofocus operation. The first and second fixed lens groups may each includetwo fixed lenses.

A further auto focus and/or auto focus zoom camera module is providedthat includes a camera module housing and an image sensor and an opticaltrain within the housing. The optical train includes at least a firstfixed lens group nearest the image sensor, a second fixed lens group,and a movable lens group disposed between the first and second fixedlens groups that is coupled to a MEMS actuator that is configured tomove the movable lens group relative to the image sensor and the firstand second fixed lens groups in an auto focus operation of the cameramodule.

The optical train may include an even number of fixed lenses. Each ofthe first and second fixed lens groups of the optical train may includetwo fixed lenses.

The first fixed lens group may include a zoom lens that is disposedclosest to the image sensor within the optical train. The second fixedlens group may be disposed along the optical path on the object side ofthe movable lens, wherein the first fixed lens group includes the zoomlens L1 and another fixed lens L2 disposed on the sensor side of themovable lens L3. The second fixed lens group may include two fixedlenses L4 and L5 on the object side of the movable lens L3. The lensdiameters may decrease from L1 to L3, and increase from L3 to L5, suchthat the movable auto focus lens L3 has the smallest diameter of thefive lenses L1-L5 from object end to image end of the optical train. Thelens L1 may be configured as a meniscus lens. The lens L2 may also beconfigured as a meniscus lens. The movable auto focus lens L3 may have abi-convex lens design. The lens L4 may be configured as a complexbi-concave lens. The lens L5 may have a complex meniscus lens design.The optical train may include an optical stop on the image side of thelens L1, and there may be stops on the scene sides of each of lenses L3,L4 and L5. The stop on L3 may be configured to move in tandem with thelens.

A MEMS actuator may be configured to move a single lens L3 of themovable lens group relative to the image sensor, and fixed lenses L1 andL2 of the first fixed lens group and fixed lenses L4 and L5 of thesecond fixed lens group may also be fixed relative to the movable lensL3. A range of movement of the lens L3 may include approximately 50 μmto 350 μm, and the range of movement of the lens L3 may be in certainembodiments approximately 100 μm.

The optical train may have been fabricated as a unitary component withinthe housing. The housing may be configured with a screw threadpermitting the focus of the camera to be set. The optical train may havebeen fabricated using passive and active alignment. The active alignmentmay have been used between the MEMS actuator and the third fixed lensL4.

A spacing between L2 and L3 may be provided within a range aroundapproximately 100 μm to 300 μm, and the MEMS actuator may be configuredto move the lens L3 along up to 90% of that spacing in an auto focusoperation. The spacing in certain embodiments between L2 and L3 may bewithin a range around approximately 190 μm. A spacing between L5 and theimage sensor may be within a range around approximately 500 μm to 1500μm. The spacing between L5 and the image sensor is in certainembodiments within a range around approximately 900 μm.

An infrared cut filter may be spaced from L5 within a range around 5 μmto 1000 μm. The infrared cut filter may be spaced in certain embodimentsfrom L5 within a range around approximately 250 μm.

A method of assembling an optical train for an auto focus and/or autofocus zoom camera module that includes five lenses (respectivelyreferred to as “L1”-“L5” in a direction from object to image along theoptical path) is also provided. The method may include in certainembodiments coupling L1 to L2; coupling L3 to a MEMS actuator, couplingL4 to L5; coupling the L1/L2 lens pair to the L3/MEMS assembly; andcoupling the L1/L2/L3/MEMS assembly to the L4/L5 lens pair. In certainembodiments the lens L5 is fabricated together with an image sensor atthe wafer level.

An auto focus MEMS camera module is also provided including an imagesensor and an auto focus module including a MEMS actuator that isconfigured to move at least one movable lens along an optical axis ofthe camera module in an auto focus operation. The auto focus moduleincludes a first fixed lens group nearest an object end of the opticalpath, and a second fixed lens group nearest the sensor end of theoptical path. The second fixed lens group is spaced from the first fixedlens group at least 100 microns to permit the at least one movable lensto move through an auto focus range of the MEMS camera module.

The second fixed lens group may be spaced from the first fixed lensgroup approximately 190 microns or more to permit the at least onemovable lens to move through an auto focus range of the MEMS cameramodule. The first and second fixed lens groups may each comprise two ormore fixed lenses that are fixed in position relative to the imagesensor or camera housing or a rigid substrate or combinations thereof.

An auto focus MEMS camera module in accordance with certain embodimentsmay include an image sensor, and an autofocus module including a MEMSactuator that is configured to move at least one movable lens in aspacing between first and second fixed lens groups along an optical axisof the camera module in an auto focus operation, wherein the imagesensor may be disposed approximately at a back focal length of one ormore fixed lenses of the second fixed lens group nearest the imagesensor.

The one or more fixed lenses of the second lens group may be configuredto compensate for a field curvature induced by the one or more movinglenses.

The one or more fixed lenses of the second lens group may be configuredto match an associated point spread function to a pixel dimension of theimage sensor approximately uniformly over an area of the image sensor.

The auto focus module may be configured such that an autofocus distancerange comprises 10 cm to 9 meters. The autofocus distance range may beapproximately 15 cm to 5 meters in certain embodiments. The auto focusmodule may be configured with an autofocus distance range betweenapproximately 20 cm to 3 meters. The autofocus distance may exclude ahyperfocal distance.

The auto focus MEMS camera module and/or a camera module enabledembedded device may include a processor and a non-transitory processorreadable storage device that has code embedded therein for programmingthe processor to perform an autofocus operation. The code may beconfigured to program the processor to correct for distortion or anotherartefact produced in a predictable manner by one or more opticalelements of the auto focus module. The code may be configured to programthe processor to process information from image sensor pixelsirrespective of a number of pixels within an image area illuminated bythe one or more optical elements. The code may be implemented inhardware or software or both.

The processor may be configured to perform the autofocus operationwithin an image processing pipeline on the image sensor. The processormay be configured to perform the autofocus operation on a discreteplatform. The discrete platform may include an image processor. Thediscrete platform may include a baseband chip in a mobile phone.

The camera module and/or camera module enabled embedded device mayinclude a machine readable file that has largely constant size andeffective image resolution irrespective of autofocus setting. A zoomfeature may range between ×0.5 and ×5. The zoom feature may rangebetween ×1 and ×4. The zoom feature may range between ×1 and ×3. Thecamera module and/or camera module enabled device may include a movablelens housing containing the one or more movable lenses. The movable lenshousing may be configured to be movable mechanically along the opticalaxis of the camera.

An auto focus MEMS camera module is also provided that includes an imagesensor and an autofocus and/or auto focus zoom module. The auto focusmodule includes a MEMS actuator that is configured to move at least onemovable lens along an optical axis of the camera module in an auto focusoperation in a spacing between a first fixed lens group, nearest theimage sensor, and a second fixed lens group, on the object end of theautofocus module. A first surface of a fixed lens of the first or secondlens group and a second surface of the at least one movable lens areprovided with one or more physical registration features configured toabut to aid alignment during assembly.

In operation of the autofocus and/or auto focus zoom module, aregistration of de-center between the one or more fixed lenses of thefirst lens group or the second lens group, or both, and the one or moremoving lenses may include approximately seven, five or three microns orless. A registration of tilt between the one or more fixed lenses of thefirst lens group or the second lens group, or both, and the one or moremoving lenses may include approximately 0.3, 0.2, or 0.1 microns orless. The optical axis may be displaced from an axis of a movable lensgroup not more than approximately 500 μm, 200 μm, or 100 μm.

A MEMS auto focus zoom camera module is also provided that includes amovable lens group, first and second fixed lens groups disposed oneither side of the movable lens group, an image sensor, and a memoryhaving embedded therein code for programming a processor to modifyacquired image data in accordance with an electronic zoom technique. Thecamera module may include an optical path that is not more than 8 mm.The movable lens group may include only a single movable lens. Aprocessor may be included that is programmable in accordance with theembedded code. A fixed lens nearest the image sensor may be configuredin accordance with the electronic zoom technique. The first and secondfixed lens groups may include a same number of fixed lenses. The firstand second fixed lens groups may each include two fixed lenses.

A method of assembly of a miniature camera module is also provided thatincludes abutting registration features of a first fixed lens group andone end of a movable lens group, affixing the movable lens group inlocation within a movable lens housing, including coupling a MEMSactuator to the movable lens group that is configured to move themovable lens group relative to the first fixed lens group in anauto-focus operation of the miniature camera module, and assembling anoptical train including coupling a second fixed lens group at the otherend the movable lens group.

The affixing may include applying an adhesive. The applying an adhesivemay include joining the movable lens housing to a sleeve. The firstfixed lens group may include first and second lenses. The method mayfurther include assembling the first fixed lens group before abuttingthe first fixed lens group and the one end of the movable lens group.The second fixed lens group may include first and second lenses, and themethod may further include assembling the second fixed lens group beforecoupling the second fixed lens group to the other end of the movablelens group.

A MEMS autofocus miniature camera module is also provided that includesone or both of a camera module housing or a rigid substrate that eitherdefines an aperture or is coupled to an aperture, or both. An imagesensor is coupled to the housing or rigid substrate. A first fixed lensgroup is coupled to the housing and is fixed relative to the imagesensor. A MEMS actuator is coupled to the housing or rigid substrate. Amovable lens group is coupled to the actuator and is movable relative tothe image sensor. A second fixed lens group is coupled to the housingand is fixed relative to the image sensor or coupled directly to theimage sensor.

A rigid substrate may be coupled to the camera module housing. A lensbarrel may contain at least the first fixed lens group and the movablelens group. The MEMS actuator may be coupled to a single movable lensfor moving the single movable lens along the optical path relative tothe image sensor between the first and second fixed lens groups. Thefirst and second fixed lens groups may each comprise one or two or morelenses. The movable lens group may include as few as a single lens. Thefirst fixed lens group and/or the second fixed lens group may includetwo lenses.

The first and second fixed lens groups may be relatively disposed oneither end of the movable lens group with a centering alignment within,e.g., 1, 3, 5 or 10 microns.

The first and second fixed lens groups may be relatively disposed oneither end of the movable lens group with a tilt alignment within, e.g.,0.01°, 0.05°, 0.1°, 0.2°, 0.3°, or 0.4°.

The first and second fixed lens groups may be relatively disposed oneither end of the movable lens group within a centering alignment in arange between of 1 micron and 10 microns or within a centering alignmentin a range, e.g., between 2 microns and 5 microns.

The first and second fixed lens groups may be relatively disposed oneither end of the movable lens group within a tilt alignment in a range,e.g., between 0.05° and 0.3°, or between 0.1° and 0.2°.

The focus travel length of the movable lens group may be, e.g., morethan 50, 100, 150, 200, 250 or 300 microns, or within a range, e.g.,between 100 microns and 300 microns, or between 50 microns and 500microns.

The first fixed lens group may be disposed a distance from the sensoralong the optical path within a range between around its back focallength ±10 microns, or between, e.g., 700 and 1100 microns, or 500 and1300 microns, may be approximately 900 microns. The first lens group andimage sensor may be relatively disposed with a centering alignmentwithin 90 microns, or in a range, e.g., between 40 microns and 140microns.

A miniature MEMS autofocus camera module is provided that includes aMEMS actuated movable lens group and at least one fixed lens groupdefining an optical axis within a camera module housing within whichobjects disposed an arbitrary distance from the camera module areautomatically focused at a determined zoom to an image sensor by MEMSactuation of the movable lens group to accomplish autofocusfunctionality.

The camera module may include a processor and embedded code forprogramming the processor to electronically zoom the image data. Theelectronic zoom may utilize both electronic and optical processingelements. The optical autofocus may also utilize both electronic andoptical processing elements. One or more lenses may participate as asame electronic and optical processing element used for both the opticalautofocus and the electronic zoom.

The at least one fixed lens group may include first and second lensgroups. The movable lens group may be disposed between the first andsecond fixed lens groups.

An optical assembly for a miniature MEMS autofocus camera module is alsoprovided including a MEMS actuated movable lens group and at least onefixed lens group defining an optical axis within a housing configured tocouple with an image sensor component to capture digital images ofobjects disposed an arbitrary distance from the camera module that areautomatically focused at a determined zoom to an image sensor portion ofthe image sensor component by MEMS actuation of the movable lens groupto accomplish autofocus functionality.

The optical assembly may include contact pads for coupling with aprocessor programmed to electronically zoom the image data. Theelectronic zoom may utilize both electronic and optical processingelements. The optical autofocus may also utilize both electronic andoptical processing elements. One or more lenses may participate as asame electronic and optical processing element used for both the opticalautofocus and the electronic zoom.

The at least one fixed lens group may include first and second lensgroups. The movable lens group may be disposed between the first andsecond fixed lens groups.

An autofocus zoom miniature MEMS camera module is provided that includesa housing with an aperture for capturing digital images, an image sensorand an optical assembly. The optical assembly is provided with at leastone fixed lens group and at least one movable lens group. A MEMSactuator is configured to move the movable lens group along an opticalaxis of the camera module relative to the image sensor and the fixedlens group to automatically focus an object at a determined zoomdisposed an arbitrary distance from the camera module onto the imagesensor.

The movable lens group may include one or more movable lenses disposednearest an object end of the optical path that are movable along theoptical axis of the camera. The fixed lens group may include one or morefixed lenses disposed between the movable lens group and the imagesensor that are fixed in position relative to the image sensor, housingor a substrate to which the image sensor is coupled, or combinationsthereof.

The image sensor may be disposed approximately at a back focal length ofthe one or more fixed lenses. The one or more fixed lenses may beconfigured to compensate for a field curvature induced by the one ormore moving lenses. The one or more fixed lenses may be configured tomatch an associated point spread function to a pixel dimension of theimage sensor approximately uniformly over an area of the image sensor.The one or more fixed and movable lenses may be configured such that anautofocus distance range comprises 10 cm to 9 m. The one or more fixedand movable lenses may be configured such that an autofocus distancerange comprises 15 cm to 5 m. The one or more fixed and movable lensesmay be configured such that an autofocus distance range comprises 20 cmto 3 m. The autofocus distance may exclude a hyperfocal distance.

An optical assembly for an autofocus zoom miniature MEMS camera moduleis also provided that includes a housing defining an aperture, one ormore lenses that are fixed relative to the housing, a MEMS actuator, andone or more movable optical elements coupled to the MEMS actuator. Anobject disposed an arbitrary distance from a camera module that includesthe optical assembly is automatically focused at a determined zoom ontothe image sensor by MEMS actuation of the one or more movable opticalelements.

The optical assembly and/or MEMS camera module may include a zoomfeature ranging between ×0.5 and ×5, or between ×1 and ×3.

The optical assembly may include a movable lens housing containing theone or more movable lenses.

An optical axis of the one or more movable optical elements may bedisplaced from an optical axis of the camera module by not more thanapproximately 0.5 mm, or by not more than approximately 0.2 mm, or bynot more than approximately 0.1 mm.

The movable and fixed lens groups may be relatively disposed with acentering alignment within 90 microns, or in a range between 40 micronsand 140 microns.

A third lens group may be fixed relative to the housing. The movablelens group may be disposed between the first and third fixed lensgroups.

The focus travel length of the second lens group may be more than 50,100, 200, or 300 microns, and/or within a range between 100 microns and300 microns or within a range between 50 microns and 500 microns.

Another autofocus zoom miniature MEMS camera module is provided thatincludes a housing, a MEMS actuator, one or more movable opticalelements coupled to the MEMS actuator, an image sensor, a processor, anda storage medium having code embedded therein for programming theprocessor to perform an autofocus zoom method. An object disposed anarbitrary distance from the camera module is automatically focused at adetermined zoom onto the image sensor by MEMS actuation of the one ormore movable optical elements.

The code may be configured to program the processor to correct fordistortion or another artifact produced in a predictable manner by oneor more optical elements of the camera. The code may be configured toprogram the processor to process information from image sensor pixelsirrespective of a number of pixels within an image area that areilluminated by the one or more optical elements.

The code may be implemented in hardware or software or both.

The processor may be configured to perform an autofocus zoom methodwithin an image processing pipeline on the image sensor.

The processor may be configured to perform the autofocus zoom method ona discrete platform. The discrete platform may include an imageprocessor or image signal processor. The discrete platform may include abaseband chip in a mobile phone. A machine readable file that haslargely constant size and effective image resolution irrespective ofautofocus zoom setting.

The camera may be configured with a zoom feature ranging between ×0.5and ×5, or between ×1 and ×4, or between ×1 and ×3.

A movable lens housing may contain the one or more movable lenses. Themovable lens housing may be configured to be movable mechanically alongthe optical axis of the camera. The MEMS actuator or another actuatormay be configured to move the movable lens housing along the opticalaxis. The movable lens housing may include one or more guide pins andone or more sleeves configured such that the guide pins are fixed inposition while the sleeves move along the guide pins.

The guide pins may be mechanically referenced to the image sensor andthe sleeves may be joined to the movable lens housing. The guide pinsmay include two or more guide pins, or three or more guide pins, or fiveor more guide pins. The guide pins may include a circular cross section.The one or more sleeves may include a shape, when viewed in section,that forms one or more area contacts to the guide pins. The shape of theone or more sleeves may include an oval shape, a “V” shape, a triangularshape, a square shape, a pentagon shape, a hexagon shape, and/or anotherpolygon shape, e.g., a regular polygon, or an irregular polygon, or theone or more sleeves may have a circular shape.

The one or more sleeves may be configured to be forced into contact withthe one or more guide pins by a lateral force. The lateral force mayinclude approximately 0.5 grams. A spring may be used to provide thelateral force. A magnet may be used to provide the lateral force.

A movable housing may include one or more guide pins and one or moreflexible components that are flexible in a direction along the opticalaxis. The guide pins may be fixed in position while the flexiblecomponents move along the guide pins. The one or more flexiblecomponents may include leaf springs that are fixedly attached to theguide pins and the movable lens housing. The one or more flexiblecomponents may include one or more opposing pairs having a spring ratethat is approximately constant through a flexure range.

The camera module housing and image sensor may define an optical axis ofthe MEMS camera module. An axis of the one or more movable opticalelements may be displaced from the optical axis of the MEMS cameramodule by not more than approximately 0.5 mm, or by not more thanapproximately 0.2 mm, or by not more than approximately 0.1 mm.

The MEMS actuator may be configured to move the one or more movablelenses within a range between 50 and 500 microns, or within a 350 micronrange, or within a 200 micron range.

A method of assembly of a miniature MEMS camera module is provided. Themethod includes abutting registration features of an optical assemblythat includes both a fixed lens group and a movable lens group includingone or more movable lenses, and affixing the movable lens group inlocation within a movable lens housing. A MEMS actuator is coupled tothe movable lens group or housing or both, whereby in use the MEMSactuator is configured to move the movable lens group relative to thefixed lens group to automatically adjust a focus distance of the opticalassembly.

The affixing may involve applying an adhesive. The applying an adhesivemay include joining the movable lens housing to a sleeve that isconfigured to couple with a pin that is fixed to the miniature cameramodule.

The method may include coupling the optical assembly with an imagesensor component, which may involve fixing the fixed lens group relativeto an image sensor portion of the image sensor component while themovable lens group or movable lens housing or both is configured to bemovable relative to the image sensor portion by actuation of the MEMSactuator to adjust said focus distance of the optical assembly. Themethod may further include coupling the image sensor component to aprinted circuit.

The miniature MEMS camera module, upon assembly, may defines an opticalaxis that is displaced from an axis of the movable lens group not morethan approximately 0.5 mm, or not more than approximately 0.2 mm, or notmore than approximately 0.1 mm.

A miniature MEMS autofocus camera module is also provided that includesa housing, an image sensor coupled to the housing, an autofocus opticalmodule coupled within the housing and including a MEMS actuator that isconfigured to move one or more movable lenses relative to one or morefixed lenses along an optical axis of the camera module to adjust afocusing distance of the autofocus optical module to automatically focusan object disposed an arbitrary distance from the camera module onto theimage sensor. This miniature MEMS autofocus optical module includes oneor more pairs of adjacent lens surfaces that include abuttingregistration features to aid in alignment. An optical assembly for theaformentioned miniature MEMS autofocus camera module is also provided.

The one or more movable lenses may be disposed nearest an object end ofthe optical path between a housing aperture and the image sensor. Theone or more fixed lenses may include at least a first fixed lensdisposed between the one or more movable lenses and the image sensor.The image sensor may be disposed approximately at a back focal length ofthe first fixed lens.

The one or more fixed lenses may include at least a second fixed lensdisposed between the object end and the one or more movable lenses, suchthat the one or more movable lenses are disposed between the first andsecond fixed lenses. The second fixed lens may be configured inaccordance with a processor-implemented zoom component to apply zoom tocaptured image data.

The miniature MEMS camera module, upon assembly, may define an opticalaxis that is displaced from an axis of the movable lens group not morethan approximately 0.5 mm, or not more than approximately 0.2 mm, or notmore than approximately 0.1 mm. The one or more fixed lenses may includefirst and second fixed lens groups each comprising one or more lensesthat are fixed relative to the image sensor. The one or more movablelenses may be disposed between the first and second fixed lens groups.

A miniature MEMS autofocus camera module is also provided that includesan image sensor and an optical assembly including a movable lens groupthat includes one or more lenses and that is coupled to a MEMS actuatorsuch that the movable lens group is movable relative to the imagesensor. The optical assembly also includes at least a first fixed lensgroup that comprises one or more lenses and that is fixed relative tothe image sensor. A processor is programmed to control an autofocusmethod designed to adjust a focus distance to an object disposed anarbitrary distance from the miniature MEMS autofocus camera module byactuating the MEMS actuator that is coupled with the movable lens group.

The optical assembly may include a second fixed lens group that includesone or more lenses that are fixed relative to the image sensor. Themovable lens group may be disposed between the first and second fixedlens groups.

A first surface of the one or more fixed lenses furthest from the imagesensor and a second surface of the one or more movable lenses nearest tothe image sensor may be provided with one or more physical registrationfeatures configured to abut to aid alignment during assembly.

A spacer may be disposed between the first and second surfaces. Thespacer may have been inserted for operation after assembly. The absenceof the spacer during assembly may have permitted the registrationfeatures of the first and second surfaces to abut. The spacer may beconfigured to achieve a separation in a range between 50 and 500microns, or in a range between 50 and 150 microns, or in a range between200 and 300 microns, or the spacer may be configured to achieve aseparation of approximately 100 microns, or approximately 250 microns.

The optical assembly may include one or more pairs of adjacent lenssurfaces that include abutting registration features.

The miniature MEMS camera module, upon assembly, may define an opticalaxis that is displaced from an axis of the movable lens group not morethan approximately 0.5 mm, or not more than approximately 0.2 mm, or notmore than approximately 0.1 mm.

In operation of the autofocus zoom module, a registration of de-centerbetween the one or more fixed lenses and the one or more moving lensesmay be approximately seven microns or less, or approximately fivemicrons or less, or approximately three microns or less.

In operation of the autofocus zoom module, a registration of tiltbetween the one or more fixed lenses and the one or more moving lensesmay be approximately 0.3 microns or less, or approximately 0.2 micronsor less, or approximately 0.1 microns or less.

An optical assembly for a miniature MEMS camera module may include anoptical assembly housing, configured for coupling with an image sensorcomponent, and an autofocus optical module coupled within the housing.The autofocus optical module includes a MEMS actuator that is configuredto move one or more movable lenses relative to one or more fixed lensesalong an optical axis to adjust a focusing distance of the autofocusoptical module.

The one or more movable lenses may be disposed nearest an object end ofthe optical path and may be movable along the optical axis. The one ormore fixed lenses may be disposed nearest an image end of the opticalpath and may be fixed in position relative to the housing. The opticalassembly housing may be configured to couple with an image sensorportion of the image sensor component that is disposed approximately ata back focal length of the one or more fixed lenses.

The one or more fixed lenses may include first and second fixed lensgroups each having one or more lenses that are fixed relative to thehousing. The one or more movable lenses may be disposed between thefirst and second fixed lens groups. The optical assembly may include oneor more pairs of adjacent lens surfaces that include abuttingregistration features. The optical assembly, upon assembly with an imagesensor component, may define an optical axis that is displaced from anaxis of the movable lens group not more than approximately 0.5 mm, ornot more than approximately 0.2 mm, or not more than approximately 0.1mm.

The optical assembly and an image sensor component may be coupled toform an autofocus camera module, whereby a registration of de-centerbetween the one or more fixed lenses and the one or more moving lensescomprises approximately seven microns or less, or approximately fivemicrons or less, or approximately three microns or less.

A registration of tilt between the one or more fixed lenses and the oneor more moving lenses of the optical assembly may comprise approximately0.3 microns or less, or approximately 0.2 microns or less, orapproximately 0.1 microns or less.

A further miniature MEMS autofocus camera module is provided thatincludes an image sensor and an optical assembly including a movablelens group that includes one or more lenses and that is coupled to aMEMS actuator such that the movable lens group is movable relative tothe image sensor. The optical assembly further includes at least a firstfixed lens group that includes one or more lenses and that is fixedrelative to the image sensor. In operation of the miniature MEMSautofocus camera module, a registration of de-center between the one ormore fixed lenses and the one or more moving lenses comprisesapproximately seven microns or less.

A first surface of a first fixed lens of the first fixed lens group anda second surface of a first movable lens of the movable lens group maybe provided with one or more physical registration features configuredto abut to aid alignment.

A first surface of the one or more fixed lenses furthest from the imagesensor and a second surface of the one or more movable lenses nearest tothe image sensor may be provided with one or more physical registrationfeatures configured to abut to aid alignment.

In operation of the autofocus zoom module, a registration of de-centerbetween the one or more fixed lenses and the one or more moving lensesmay comprise approximately five microns or less, or approximately threemicrons or less.

In operation of the autofocus zoom module, a registration of tiltbetween the one or more fixed lenses and the one or more moving lensescomprises approximately 0.3 microns or less, or approximately 0.2microns or less, or approximately 0.1 microns or less.

A spacer may be disposed between the first and second surfaces. Thespacer may have been inserted for operation after assembly. The absenceof the spacer during assembly may have permitted the registrationfeatures of the first and second surfaces to abut. The spacer may beconfigured to achieve a separation in a range between 50 and 500microns, or in a range between 50 and 150 microns, or in a range between200 and 300 microns, or the spacer may be configured to achieve aseparation of approximately 100 microns, or approximately 250 microns.

Another miniature MEMS-actuated camera module is provided that includesone or both of a camera module housing or a rigid substrate that eitherdefines an aperture or is coupled to an aperture, or both. An imagesensor is coupled to the one or both of the camera module housing orrigid substrate. A first lens group is coupled to the housing and fixedrelative to the image sensor or coupled directly to the image sensor orboth. A MEMS actuator is coupled to the housing or rigid substrate. Asecond lens group is coupled to the actuator and is movable relative tothe image sensor.

An optical assembly for the miniature MEMS camera module may include ahousing that either defines an aperture or is coupled to an aperture, orboth, and that is configured to couple with an image sensor componentfor focusing images with said optical assembly onto an image sensorportion of said image sensor component when said housing is coupled tosaid image sensor component, a first lens group coupled to and fixedrelative to the housing, a MEMS actuator coupled to the housing, and asecond lens group coupled to and movable with the MEMS actuator relativeto the first lens group.

A rigid substrate may be coupled to the camera module housing.

A lens barrel may contain at least the second lens group.

The MEMS actuator may be coupled to one, two, three, four or more lensesof the second lens group for moving the one, two, three, four or morelenses along the optical path relative to the image sensor.

The second lens group may include four lenses. The first lens group mayinclude a single lens.

The second lens group may include a single movable lens. The first lensgroup may include two fixed lenses. A third lens group may include oneor two more fixed lenses. The second lens group may be disposed andmovable through an autofocus range between the first and third fixedlens groups.

The first and second lens groups may be relatively disposed with acentering alignment within 1 micron, or within 3 microns, or within 5microns, or within 10 microns.

The first and second lens groups may be relatively disposed with a tiltalignment within of 0.01°, or within 0.05°, or within 0.1°, or within0.2°, or within 0.3°, or within 0.4°.

The first and second lens groups may be relatively disposed within acentering alignment in a range between of 1 micron and 10 microns, or ina range between 2 microns and 5 microns.

The first and second lens groups may be relatively disposed within atilt alignment in a range between 0.05° and 0.3°, or in a range between0.1° and 0.2°.

The focus travel length of the second lens group may be more than 50microns, or more than 100 microns, or more than 150 microns, or morethan 200 microns, or more than 250 microns, or more than 300 microns, orwithin a range between 100 microns and 300 microns, or within a rangebetween 50 microns and 500 microns.

The first lens may be disposed a distance from the sensor along theoptical path within a range between around its back focal length ±10microns. The back focal length may include between 700 and 1100 microns,or between 500 and 1300 microns, or approximately 900 microns.

The second lens group and image sensor may be relatively disposed with acentering alignment within 90 microns, or in a range between 40 micronsand 140 microns.

A third lens group may be coupled to the housing and fixed relative tothe image sensor. The second lens group which is movable relative to theimage sensor may be disposed between the first and third lens groupswhich are each fixed relative to the image sensor.

A further variation of a variable optic camera is a camera wherein theoptical train is divided into groups, some of which are fixed infunctionality and position and others of which are variable infunctionality and position. By this means, more advanced control of theoptical train can be accomplished. For example, by moving two particulargroups of lenses along the optical axis, the field of view of the cameracan be altered. Because the resolution of a camera is generally fixed bycertain other parameters, restricting the field of view results ineffective magnification of objects in the scene. Consequently, camerasof this type are referred to as ‘zoom’.

Several embodiments are described of advantageous auto focus zoomcameras and camera modules, and/or components or subsets of features ofauto focus zoom cameras. In one embodiment, auto focus and zoomfunctionality is accomplished through a combination of one lens ofspecial design that is fixed in position, a single lens that can bemoved along the optical axis of the camera and an algorithm that makeschanges to the electronic form of the image. Related embodiments andalternative features relating especially to the zoom feature of thisembodiment may be described at US reissue patent RE42,898 and at USpublished patent applications nos. US2009/0115885 and US2009/0225171 andare incorporated by reference. In another embodiment, zoom functionalityis provided by one or more additional moving lenses. The single lensthat can be moved in the electronic zoom embodiment may be one that issited in the middle of the optical train and that is movable to provideauto focus functionality. More than a single lens may be movable inother embodiments, and more than one fixed lens are included in otherembodiments.

Certain other optical components are included in various combinations indifferent embodiments, such as one or more stops, apertures and/or aninfrared filter that are not always specifically mentioned with eachembodiment. The infrared filter may be included between the image sensorand the last lens of the optical train, or elsewhere along the opticalpath. One or more apertures may be fixed at a surface of lens orindependently fixed to the camera module housing or to a lens barrelhousing or other fixed component of the camera module or camera device.One or more apertures may move, such as a movable aperture on or withthe movable lens. In certain embodiments, an aperture for the movablelens is movable as being on or near the surface of the movable lens orotherwise fixed relative to the movable lens so that the aperture andmovable are movable together using the actuator. In other embodimentsthe aperture for the movable lens can be fixed relative to the imagesensor.

The special lens of the electronic zoom embodiment accomplishes zoom bymatching the so-called point spread function (PSF) of the optical trainto the image sensor. PSF is a quantity that describes the extent towhich a theoretical point of light of zero area would expand as itpasses through the optical train of the camera. The expansion occurs dueto defects in the materials used for the lenses, surface imperfections,alignment tolerances and a host of other factors. The lower the qualityof the optical train, the larger the PSF will be. A good match betweenthe optical train and image sensor occurs when the PSF matches thedimensions of the pixels in the image sensor. If the optical train isover-specified, the point of light will spread only slightly and remainsmaller than one pixel. Conversely, if the optical train isunder-specified, the point of light will spread excessively to coverseveral pixels resulting in a blurred image.

The PSF of the optical train may vary with the radius, e.g., beingsmaller at the centre than in the middle. This means that there may be amismatch between the PSF and pixel size across the lens radius. Ideallythe pixels in the centre would be smaller than those at the periphery tomatch the variation in PSF function across the lens radius; this is howthe eyes of birds of prey are configured. Unfortunately manufacture ofimage sensors with a non-uniform distribution of pixels is not widelyavailable at the moment because they are not (yet) economically viable.One solution is to set the PSF to match the pixel size at about twothirds of the lens radius. This produces an image that is sharp in thecentre and slightly blurred at the edges, but is probably acceptable incertain embodiments since the objects of greatest interest in the sceneare usually in the centre of the image.

It is possible to include in an optical train a special lens so that atthe periphery the PSF matches the pixel size of the imager. If thisoptic design were continued inwards it would result in the lens beingover-specified since the PSF decreases towards the optical axis. Thisproblem is overcome in certain embodiments by increasing themagnification of the optical system towards the centre. Magnificationwill increase the effective size of the point of light and hence theeffective PSF. The magnification may be set in certain embodiments to besufficient so that the PSF matches the pixel size over the entire areaof the imager. The result is that the lens has higher magnification inthe centre than at the periphery.

An electronic camera incorporating a special lens of the type describedis able to provide for dynamic alteration of the field of view, in otherwords zoom, by imaging cropping. While cropping usually decreases imagequality since information from the scene is discarded, the fidelity ofthe cropped image is preserved in certain embodiments because the centreof the image has been magnified by the special lens. The special opticused in certain embodiments to produce a dynamic field of view camerawill produce distortion of the image that resembles barrel distortion.The extent of the distortion is fixed and controlled by the lens design.This makes it relatively efficient to correct and remove distortion andother predictable artefacts by configuring the image data in an imageprocessing operation performed by an on-board processor, or otherprocessor, programmed by a certain algorithm designed for the specificpurpose. A camera with zoom based on this principal of operation may bedescribed in U.S. Pat. RE42,898, US published patent applications nos.2012/0063761, 2011/0221936, 2011/0216158, 2009/0115885 and 2009/0225171,and/or U.S. patent application Ser. Nos. 61/609,293 and 13/445,857,which are all incorporated by reference. The algorithm may be stored onthe camera module or outside the camera module within an electronicdevice within which the camera module is a component, or on the cloud orotherwise as long as it is accessible by a processor of the cameramodule or device or external component that is configured to apply thealgorithm to image data, e.g., raw data from the image sensor orpre-processed image data, that is not yet stored, transmitted ordisplayed as permanent image data until the processor applies thealgorithm to the data so that the image may be displayed with theappearance of zoom magnification.

The special fixed lens involved in producing zoom in combination with analgorithm is, for reasons of physics in certain embodiments, the lensclosest to the image sensor. Alternative approaches to add auto focusmay involve moving one or more other lenses in the optical train as agroup. An auto focus zoom camera based on this principal of operation isdescribed in U.S. Patent application Ser. No. 61/609,293. This movablelens group may contain more than one movable lens, and may contain fourlenses as described in the '293 application, as well as various numbersof stops and apertures depending on the particular number and geometryof the lens or lenses forming the movable lens group. The embodimentswherein only a single lens is included in the movable lens group, suchas the middle lens L3 being movable relative to two pairs of fixedlenses L1-L2 and L4,-L5 located on either side of the middle lens L3,have an advantage of smaller mass and thus a relatively lower force isinvolved in moving it, and even has a surprising further advantage thata smaller displacement range actuator may be used.

Another feature of an auto focus zoom camera module in accordance withcertain embodiments involves the realisation of auto focus incombination with zoom from a special lens of the type described above,by moving the middle lens in the optical train in certain embodiments,e.g., L3 in an optical train including five lenses or L5 in an opticaltrain of seven lenses. In other embodiments, the movable lens is offsetfrom the middle somewhere between at least one fixed lens and the restof the optical train, e.g., L2 or L4 in the five lens embodiment or L2,L3, L5 or L6 in the seven lens embodiment. Still other embodimentsinvolve movable lenses at one or both ends of the optical train.

A schematic representation of an example of an optical train configuredwith a movable middle lens is given in FIG. 1. Contrary to perceivedexpectation, it transpires that to achieve a similar focus range to aconventional auto focus camera, the middle lens is moved a relativelyshort distance, typically around 100 μm. This makes possible the use ofnovel forms of actuator, such as MEMS, to move the lens and a number ofconsequential benefits arising from the inherent characteristics of suchdevices. Of the many benefits of this design, small size, low powerconsumption, low noise, high speed and high accuracy of movement andother improvements are provided.

By way of non-limiting and non-exhaustive examples, certain embodimentswill now be described in detail with reference to FIGS. 1-6.

Reference is made to FIG. 1, which is a schematic representation of anauto focus zoom camera in accordance with certain embodiments. Thecamera comprises the two general components mentioned above, namely anoptical train 101 and an image sensor 102. Only the lenses of theoptical train are shown in the interests of clarity. In variousembodiments, the optical train may include a number of other elements,including stops, apertures and an infrared filter particularly when asilicon-based image sensor is being used. The optical train in theexample illustrated at FIG. 1 includes five lenses. Traditionally thelens nearest the scene 103 is designated L1 and progressing L2, L3 etc.in a direction towards the image sensor. The lenses are desirablyaligned in tilt, centering and rotation to the optical axis 104 of thecamera. The fixed lenses can be considered to be in two fixed groups.The upper fixed group 105, comprising L1 and L2, is nearest the scene,while the lower fixed group 106 comprising L4 and L5, is nearest theimage sensor. Lens L5 is the special lens that provides the describedzoom function in combination with the algorithm. Lens L3 is the middlelens in the optical train. As indicated by the bi-directional arrow,this lens has a range of travel along the optical axis of the camera foradjusting focus.

FIG. 2 shows one possible embodiment of lens profiles suitable for theoptical train of the MEMS autofocus miniature camera module of FIG. 1.As shown, L1 and L2 are predominantly meniscus lenses facing the scenein the example of FIG. 2. Lens L3 is generally bi-convex, but may havevariable curvature along its radius. LA may have a complex profileincluding different directions or degrees of curvature at differentpoints along its radius, and is superficially bi-concave in the exampleillustrated at FIG. 2. L5 may be referred to as a complex meniscus lensfacing the image sensor or a fish eye lens in certain embodiments or maybe the same as or similar to a lens or lenses described in U.S. RE42,898and/or US2009/0115885 and/or US2009/0225171. By complex meniscus, it ismeant that the two surfaces are at least generally curved in the samedirection, convex or concave, but do not have to have the same directionof curvature all along the radius of the lens surface and/or may havedifferent degrees of curvature at different radii. For example, the lensL5, illustrated by example in FIG. 2, includes a back surface that has asmall area in the middle that is concave, while the rest of the backsurface of L5 has a convex curvature and the front surface is concave,resulting in what may be referred to as complex meniscus.

The lens diameters decrease from L1 to L3, then increase from L3 to L5in the example illustrated at FIG. 2. In general, the movable lens,e.g., L3 in this example, may have a smaller diameter than the fixedlenses of the optical train to accommodate the micro-electro-mechanicalsystem, or MEMS, actuator component that is coupled with the movablelens, while the fixed lenses may have same or similar diameters relativeto each other. Also indicated in FIG. 2 by horizontal lanes on lenssurfaces 201 are the positions of optical stops in accordance withcertain embodiments. Lenses L3, L4 and L5 have optical stops on thescene side on the lens, while L1 has a stop on the image side of thelens. The stop on L3 may move in tandem with the lens.

Consideration of the optical design reveals that to achieve a wide rangeof focus from very close to the camera to very removed, L3 will have astroke of about 100 μm or more. L3 may be spaced from L2 by a gap ofabout 190 μm when the actuator is at rest, while the actuator isconfigured according to its motion, in certain embodiments, so that thegap decreases when the focus is altered.

In certain embodiments L3 is moved by a MEMS actuator. Suitable MEMSactuators are described in several of the US patents and US patentapplications incorporated by reference herein below. Another MEMSactuator having a somewhat different design is described in US-PCTapplication no. PCT/US2012/024018. Such actuators can be fabricated insilicon or substantially polymeric materials and have a stroke of around100 μm. They also exhibit a number of other beneficial characteristics,which are conferred on a MEMS auto focus miniature camera module or on aMEMS auto focus zoom miniature camera module of the type described.These include, very low power consumption, small optical path distanceand small Z dimension thickness, fast and precise actuation, low noise,negligible particulate contamination and low cost.

A MEMS actuator in accordance with certain embodiments may be thought ofas generally a unidirectional device, setting aside for the moment anycentering or tilt alignment movements that may be ascribed to anactuator component. That is, a MEMS actuator in accordance with certainembodiments has a rest position and the actuator can be driven from thatrest position in one dimension only. This has a benefit for the assemblyof auto focus camera modules in that it permits the entire lens train,or a substantial portion thereof, to be assembled as a pre-alignedunitary component. For subsequent assembly and calibration steps, it canthen be handled similarly to or in exactly the same manner as the lenstrain of a fixed focus camera, namely the focus can be set by insertinga holder, containing the lens train into a sleeve fixed over the imagesensor. In certain embodiments, the holder and sleeve are coupled by ascrew thread.

FIG. 3 schematically illustrates a cross-section through a MEMS autofocus zoom miniature camera module or MEMS autofocus miniature cameramodule in accordance with certain embodiments that utilizes assemblywith the lens train fabricated as a pre-aligned unitary component. Theimage sensor 301 in this embodiment resides on a substrate 302 to whichis attached a sleeve 303. The sleeve has a screw thread 304. The holder305 containing the lens train 306 has a mating screw thread 307.Rotating the holder with respect to the sleeve moves the entire lenstrain, in this example embodiment, along the optical axis 308 of thecamera, permitting the focus to be set.

For an optic train to transmit images at high fidelity involvesalignment of the various elements of the train, principally the lenses,with respect to tilt, centering and rotation with respect to one anotherto a certain degree of accuracy. While it is possible to achieve veryexact alignment of one lens to another using active alignment techniquesin certain embodiments, passive methods are used in several embodiments,and typically wherever possible, due to the high speed of assembly andlow cost of this approach. In a MEMS auto focus miniature camera modulein accordance with certain embodiments, passive alignment tolerances areaccommodated in all but one of the joints of the lens train. This is theexample arrangement that is illustrated in FIG. 4. The passive alignmentfeatures are indicated by cups and cones, in the interests of clarity,although possible sizes and geometries of passive alignment features aremultitudinous. The passive alignment features include physical featuresthat mate in such a manner so as to eliminate one or more degrees offreedom, and may perhaps eliminate all of them, or at least as manydegrees of misalignment as possible. Passive alignment in accordancewith certain embodiments achieves alignment in all axes better than +/−5μm, and in some embodiments substantially smaller. Starting from theimage sensor upwards, L4 is aligned to L5 by a passive alignment feature401. Active alignment 402 is used between the MEMS actuator and L4. Thispermits L3 to be aligned to the MEMS actuator 403 by passive alignment404. L2 is aligned to the MEMS actuator, and thereby L3 by passivealignment 405. L1 is also aligned to L2 by passive alignment 406. Apassive alignment technique that is used in certain embodiments may bereferred to as ‘lens stacking’.

A method of assembling the optical train in accordance with certainembodiments is as follows (see FIG. 5 and FIG. 6). In one example, L1 isjoined to L2 to form a first sub-assembly G1. L3 is joined to the MEMSactuator to form a second sub-assembly G2. L4 is joined to L5 to form athird sub-assembly G3. These lens assembly operations include the stopsassociated with each lens. G1 is then assembled on G2 to formsub-assembly G4. Finally, G4 is assembled on G3. In certain embodiments,active alignment is used to align G3 and G4 to form G5. Active alignmentmay include fixing two groups such as G3 and G4 in position, e.g., usingUV cured adhesive or clamp or other fastening component or technique,once alignment has been achieved.

When the optical train is complete, it is desirable in certainembodiments to add one additional component, namely an infrared cutfilter between the lower lens L5 and the image sensor. In a typicaldesign the distance between L5 and the infrared cut filter will be about250 μm. This is possible because an infrared cut filter will typicallybe around 100-300 μm in thickness and the distance between L5 and theimage sensor may be approximately 900 μm in an example embodiment. Otherdesigns, such as those described at U.S. Ser. No. 13/445,857, which isincorporated by reference, may be advantageously included, in whole orin part in an advantageous MEMS auto focus miniature camera module orMEMS auto focus zoom miniature camera module.

While an exemplary drawings and specific embodiments of the presentinvention have been described and illustrated, it is to be understoodthat that the scope of the present invention is not to be limited to theparticular embodiments discussed. Thus, the embodiments shall beregarded as illustrative rather than restrictive, and it should beunderstood that variations may be made in those embodiments by workersskilled in the arts without departing from the scope of the presentinvention.

In addition, in methods that may be performed according to preferredembodiments herein and that may have been described above, theoperations have been described in selected typographical sequences.However, the sequences have been selected and so ordered fortypographical convenience and are not intended to imply any particularorder for performing the operations, except for those where a particularorder may be expressly set forth or where those of ordinary skill in theart may deem a particular order to be necessary.

In addition, all references cited herein are incorporated by reference,as well as the background, abstract and brief description of thedrawings, and U.S. applications 61/657,012, 61/675,812, 61/622,480,13/541,650, 13/767,877, 12/213,472, 12/225,591, 12/289,339, 12/774,486,13/026,936, 13/026,937, 13/036,938, 13/027,175, 13/027,203, 13,027,219,13/051,233, 13/163,648, 13/264,251,13/445,857, 13/571,405 and PCTapplication WO2007/110097, and U.S. Pat. No. 6,873,358, and RE42,898 areeach incorporated by reference into the detailed description of theembodiments as disclosing alternative embodiments.

Components of MEMS actuators that may be included with a camera modulethat includes a movable optic or optical group in accordance withalternative embodiments are described at U.S. Pat. Nos. 7,972,070,8,014,662, 8,090,252, 8,004,780, 7,747,155, 7,990,628, 7,660,056,7,869,701, 7,844,172, 7,832,948, 7,729,601, 7,787,198, 7,515,362,7,697,831, 7,663,817, 7,769,284, 7,545,591, 7,792,421, 7,693,408,7,697,834, 7,359,131, 7,785,023, 7,702,226, 7,769,281, 7,697,829,7,560,679, 7,565,070, 7,570,882, 7,838,322, 7,359,130, 7,345,827,7,813,634, 7,555,210, 7,646,969, 7,403,344, 7,495,852, 7,729,603,7,477,400, 7,583,006, 7,477,842, 7,663,289, 7,266,272, 7,113,688,7,640,803, 6,934,087, 6,850,675, 6,661,962, 6,738,177, and 6,516,109;and at

US published patent applications nos. 2010/030843, 2007/0052132,2011/0317013, 2011/0255182, 2011/0274423, and at

U.S. patent application Ser. Nos. 13/302,310, 13/247,938, 13/247,925,13/247,919, 13/247,906, 13/247,902, 13/247,898, 13/247,895, 13/247,888,13/247,869, 13/247,847, 13/079,681, 13/008,254, 12/946,680, 12/946,670,12/946,657, 12/946,646, 12/946,624, 12/946,614, 12/946,557, 12/946,543,12/946,526, 12/946,515, 12/946,495, 12/946,466, 12/946,430, 12/946,396,12/873,962, 12/848,804, 12/646,722, 12/273,851, 12/273,785, 11/735,803,11/734,700, 11/848,996, 11/491,742, and at

USPTO-Patent Cooperation Treaty applications nos. PCT/US12/24018,PCT/US11/59446, PCT/US11/59437, PCT/US11/59435, PCT/US11/59427,PCT/US11/59420, PCT/US11/59415, PCT/US11/59414, PCT/US11/59403,PCT/US11/59387, PCT/US11/59385, PCT/US10/36749, PCT/US07/84343, andPCT/US07/84301.

The following are also incorporated by reference as disclosingalternative embodiments:

U.S. Pat. Nos. 8,363,952, 8,358,841, 8,417,055, 8,422,739, 8,285,001,8,055,029, 7,855,737, 7,995,804, 7,970,182, 7,916,897, 8,081,254,7,620,218, 7,995,855, 7,551,800, 7,515,740, 7,460,695, 7,965,875,7,403,643, 7,916,971, 7,773,118, 8,055,067, 7,844,076, 7,315,631,7,792,335, 7,680,342, 7,692,696, 7,599,577, 7,606,417, 7,747,596,7,506,057, 7,685,341, 7,694,048, 7,715,597, 7,565,030, 7,636,486,7,639,888, 7,536,036, 7,738,015, 7,590,305, 7,352,394, 7,564,994,7,315,658, 7,630,006, 7,440,593, 7,317,815, and 7,289,278; and

United States published patent applications serial nos. 2012/0019614,2012/0019613, 2012/0008002, 2011/0216156, 2011/0205381, 2012/0007942,2011/0141227, 2011/0002506, 2011/0102553, 2010/0329582, 2011/0007174,2010/0321537, 2011/0141226, 2010/0141787, 2011/0081052, 2010/0066822,2010/0026831; 2009/0303343, 2009/0238419, 2010/0272363, 2009/0189998,2009/0189997, 2009/0190803, 2009/0179999, 2009/0167893, 2009/0179998,2008/0309769, 2008/0266419, 2008/0220750, 2008/0219517, 2009/0196466,2009/0123063, 2008/0112599, 2009/0080713, 2009/0080797, 2009/0080796,2008/0219581, 2009/0115915, 2008/0309770, 2007/0296833, 2007/0269108;and

U.S. patent application Ser. Nos. 13/306,568, 13/282,458, 13/234,149,13/234,146, 13/234,139, 13/220,612, 13/084,340, 13/078,971, 13/077,936,13/077,891, 13/035,907, 13/028,203, 13/020,805, 12/959,320, 12/944,701,and 12/944,662.

1. (canceled)
 2. A miniature camera module comprising: a substrate; an image sensor mounted on said substrate; a housing mounted on said substrate; a lens holder adjustably coupled to said housing; a micro-electro-mechanical system (MEMS) actuator disposed within said lens holder; and an optical train disposed within said lens holder, said optical train including a first fixed lens group, a second fixed lens group, and at least one movable lens coupled to said MEMS actuator and disposed between said first and said second fixed lens groups; and wherein said MEMS actuator is configured to move said at least one movable lens relative to said image sensor and said first and said second fixed lens groups in an auto-focus operation of said camera module.
 3. The miniature camera module of claim 2, wherein: said housing comprises a sleeve mounted on said substrate; and said lens holder is adjustably mounted within said sleeve.
 4. The miniature camera module of claim 3, wherein: said sleeve includes a thread set on an interior surface thereof; and said lens holder includes a complementary thread set on an exterior surface thereof, said complementary thread set rotatably engaging said thread set of said sleeve to facilitate adjustment of the position of said optical train along an optical axis of said miniature camera module.
 5. The miniature camera module of claim 2, wherein: said MEMS actuator is fixedly aligned between said first and said second fixed lens groups; and said optical train is installed in said lens holder as a pre-aligned, unitary component.
 6. The miniature camera module of claim 5, wherein: said MEMS actuator defines a rest position of said at least one movable lens; said MEMS actuator drives said movable lens from said rest position toward said first fixed lens group; a gap between said movable lens in said rest position and a nearest lens of said first fixed lens group is less than or equal to 190 micrometers; and a stroke of said MEMS actuator is approximately 100 micrometers.
 7. The miniature camera module of claim 5, wherein: said first fixed lens group includes passive alignment features; said MEMS actuator includes complementary passive alignment features; and mating said passive alignment features and said complementary passive alignment features accomplishes alignment between said MEMS actuator and said first fixed lens group to better than +/−5 micrometers in all axes.
 8. The miniature camera module of claim 2, wherein a focus travel length of said at least one movable lens is within a range between 100 micrometers and 300 micrometers.
 9. The miniature camera module of claim 2, wherein said first and said second fixed lens groups are relatively disposed on either side of said at least one movable lens within a centering alignment between 2 micrometers and 5 micrometers.
 10. The miniature camera module of claim 2, wherein said first and said second fixed lens groups are relatively disposed on either side of said at least one movable lens within a tilt alignment of less than or equal to 0.4 degrees.
 11. The miniature camera module of claim 2, wherein said MEMS actuator is fabricated in silicon.
 12. A method of assembling a miniature camera module, said method comprising: providing a housing; providing a lens holder; providing a first fixed lens group; providing a second fixed lens group; providing a movable lens group; providing a micro-electro-mechanical system (MEMS) actuator configured to move said movable lens group relative to said first and said second fixed lens groups in an auto-focus operation of said miniature camera module; assembling an optical train including coupling said movable lens group to said MEMS actuator, coupling said first fixed lens group on a first side of said MEMS actuator, and coupling said second fixed lens group on a second side of said MEMS actuator; affixing said optical train within said lens holder; and adjustably coupling said lens holder, including said optical train, to said housing.
 13. The method of claim 12, wherein: said movable lens group comprises a single lens; and said step of coupling said movable lens group to said MEMS actuator includes mating a first set of passive alignment features of said single lens with a complementary second set of passive alignment features of said MEMS actuator.
 14. The method of claim 13, wherein: said step of coupling said first fixed lens group on said first side of said MEMS actuator occurs after said step of coupling said single lens to said MEMS actuator; and said step of coupling said first fixed lens group on said first side of said MEMS actuator includes mating a third set of passive alignment features of said first fixed lens group with a complementary fourth set of passive alignment features disposed on said first side of said MEMS actuator.
 15. The method of claim 14, wherein said step of coupling said second fixed lens group on said second side of said MEMS actuator includes actively aligning said second fixed lens group on said second side of said MEMS actuator.
 16. The method of claim 12, wherein said step of providing said first fixed lens group includes: providing a first lens element including a first set of passive alignment features; providing a second lens element including a second set of passive alignment features complimentary to said first set of passive alignment features; and assembling said first fixed lens group by mating said first and said second sets of passive alignment features before coupling said first fixed lens group on said first side of said MEMS actuator.
 17. The method of claim 16, wherein said step of providing said second fixed lens group includes: providing a third lens element including a third set of passive alignment features; providing a fourth lens element including a fourth set of passive alignment features complimentary to said third set of passive alignment features; and assembling said second fixed lens group by mating said third and said fourth sets of passive alignment features before coupling said second fixed lens group on said second side of said MEMS actuator.
 18. The method of claim 12, further comprising: a substrate; and an image sensor mounted on said substrate; and wherein said housing comprises a sleeve mounted on said substrate; and said lens holder is adjustably mounted within said sleeve.
 19. The method of claim 18, wherein: said sleeve includes a thread set on an interior surface thereof; said lens holder includes a complementary thread set on an exterior surface thereof, said complementary thread set rotatably engaging said thread set of said sleeve; and said step of adjustably coupling said lens holder to said housing includes rotating said lens holder to adjust the position of said optical train along an optical axis of said miniature camera module.
 20. The method of claim 12, wherein: said movable lens group comprises a single movable lens; said MEMS actuator defines a rest position of said single movable lens; said MEMS actuator is configured to drive said single movable lens from said rest position toward said first fixed lens group; a gap between said single movable lens in said rest position and a nearest lens of said first fixed lens group is less than or equal to 190 micrometers; and a stroke of said MEMS actuator is approximately 100 micrometers.
 21. The method of claim 12, wherein: said first fixed lens group includes passive alignment features; said MEMS actuator includes complementary passive alignment; and mating said passive alignment features and said complementary passive alignment features accomplishes alignment between said MEMS actuator and said first fixed lens group to better than +/−5 micrometers in all axes. 